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Subject[dhowells-fs:fscache-rewrite-indexing 75/75] fs/cachefiles/io.c:477:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false
tree:   https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git fscache-rewrite-indexing
head: 96d4e1af98c26988d3c1b3cf688974c24de90fa9
commit: 96d4e1af98c26988d3c1b3cf688974c24de90fa9 [75/75] cachefiles: Add error injection support
config: hexagon-randconfig-r041-20211014 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 6c76d0101193aa4eb891a6954ff047eda2f9cf71)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?id=96d4e1af98c26988d3c1b3cf688974c24de90fa9
git remote add dhowells-fs https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
git fetch --no-tags dhowells-fs fscache-rewrite-indexing
git checkout 96d4e1af98c26988d3c1b3cf688974c24de90fa9
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> fs/cachefiles/io.c:477:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (pos == 0)
^~~~~~~~
fs/cachefiles/io.c:480:6: note: uninitialized use occurs here
if (ret < 0) {
^~~
fs/cachefiles/io.c:477:2: note: remove the 'if' if its condition is always true
if (pos == 0)
^~~~~~~~~~~~~
fs/cachefiles/io.c:422:9: note: initialize the variable 'ret' to silence this warning
int ret;
^
= 0
1 warning generated.


vim +477 fs/cachefiles/io.c

409
410 /*
411 * Prepare for a write to occur.
412 */
413 static int __cachefiles_prepare_write(struct netfs_cache_resources *cres,
414 loff_t *_start, size_t *_len, loff_t i_size,
415 bool no_space_allocated_yet)
416 {
417 struct cachefiles_object *object = cachefiles_cres_object(cres);
418 struct cachefiles_cache *cache = object->volume->cache;
419 struct file *file = cachefiles_cres_file(cres);
420 loff_t start = *_start, pos;
421 size_t len = *_len, down;
422 int ret;
423
424 if (!file) {
425 if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE))
426 return -ENOBUFS;
427 file = cachefiles_cres_file(cres);
428 if (!file)
429 return -ENOBUFS;
430 }
431
432 /* Round to DIO size */
433 down = start - round_down(start, PAGE_SIZE);
434 *_start = start - down;
435 *_len = round_up(down + len, PAGE_SIZE);
436
437 /* We need to work out whether there's sufficient disk space to perform
438 * the write - but we can skip that check if we have space already
439 * allocated.
440 */
441 if (no_space_allocated_yet)
442 goto check_space;
443
444 pos = cachefiles_inject_read_error();
445 if (pos == 0)
446 pos = vfs_llseek(file, *_start, SEEK_DATA);
447 if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
448 if (pos == -ENXIO)
449 goto check_space; /* Unallocated tail */
450 trace_cachefiles_io_error(object, file_inode(file), pos,
451 cachefiles_trace_seek_error);
452 return pos;
453 }
454 if ((u64)pos >= (u64)*_start + *_len)
455 goto check_space; /* Unallocated region */
456
457 /* We have a block that's at least partially filled - if we're low on
458 * space, we need to see if it's fully allocated. If it's not, we may
459 * want to cull it.
460 */
461 if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE) == 0)
462 return 0; /* Enough space to simply overwrite the whole block */
463
464 pos = cachefiles_inject_read_error();
465 if (pos == 0)
466 pos = vfs_llseek(file, *_start, SEEK_HOLE);
467 if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
468 trace_cachefiles_io_error(object, file_inode(file), pos,
469 cachefiles_trace_seek_error);
470 return pos;
471 }
472 if ((u64)pos >= (u64)*_start + *_len)
473 return 0; /* Fully allocated */
474
475 /* Partially allocated, but insufficient space: cull. */
476 pos = cachefiles_inject_remove_error();
> 477 if (pos == 0)
478 ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
479 *_start, *_len);
480 if (ret < 0) {
481 trace_cachefiles_io_error(object, file_inode(file), ret,
482 cachefiles_trace_fallocate_error);
483 cachefiles_io_error_obj(object,
484 "CacheFiles: fallocate failed (%d)\n", ret);
485 ret = -EIO;
486 }
487
488 return ret;
489
490 check_space:
491 return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE);
492 }
493

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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